The present invention relates to a method of processing a cylindrical surface and, more particularly, to a method for mechanically processing an inner or outer cylindrical surface of a cylindrical part in which a punch in the cylindrical part and a die fitted to the outside of the cylindrical part are moved relatively to each other in an axial direction of the cylindrical part to impart a tension to the processed surface to effect a plastic deformation, to thereby form grooves or teeth in the processed surface.
Hitherto, cutting work has been adopted as a major processing method for producing cylindrical parts having grooves or teeth in the inner or outer peripheral surface thereof such as parts having a helical involute spline in the cylindrical surface, e.g. the outer part of one-way clutch of automotive starter, parts for automotive transmission and so forth. The cutting work, however, suffers various disadvantage such as uneconomically high cost of the tool, short life of the tool requiring frequent grinding and impractically long processing time attributable to the inferior working efficiency. Consequently, the processing of cylindrical surface by cutting work raises the overall cost of the products. This is quite disadvantageous from the view point of mass-production of parts, particularly automotive parts.
In recent years, approaches have been made to the utilization of plastic work for forming grooves, teeth or the like in the cylindrical surface but such a technique encounters various difficulties when applied to the formation of helical gear teeth or helical involute spline.
Namely, in the known method of processing of cylindrical surface of a cylindrical member by a plastic deformation, the plastic deformation of the blank material is made solely by the compression applied to the blank, so that the blank can hardly be deformed to require a large force for driving the punch. In addition, since the blank material is pressed by a force greater than the resistance to the compression, a seizure is liable to occur between the punch and the blank or between the die and the blank. In addition, the grooves or teeth cannot be formed at sufficiently high precision. In other words, this known method relying upon compression deformation is to forcibly deform the blank while keeping the latter under a condition resisting to the deformation. Consquently, this method could process, when applied to the production of a part having a helical involute spline in its inner peripheral surface, only a small helical angle of about 18.degree. or less. Namely, helical angle in excess of 18.degree. could not be processed by this known method because of a seizure of the punch.